JP2006329301A - Charge structure for hydrostatic continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charge structure for supplying oil discharged from a charge pump to an oil filter and supplying oil purified by an oil filter to a charge oil path without using an external pipe. <P>SOLUTION: A hydrostatic continuously variable transmission 5 having a port block 21 connected to a shift casing 2b is connected to the end face of a transmission case 3 so that the port block 21 is located on the side of the transmission case. The charge pump CP is mounted at the port block 21 on the side of the transmission case. Oil discharged from the charge pump CP is guided and supplied to an oil filter 28 mounted on the outer face of the transmission case 3 via the port block 21, the transmission casing 2b, and internal oil paths, e, f, g formed in the wall of the transmission case 3. Oil passing through the oil filter 28 is guided to the charge oil path of the port block 21 via the transmission case 3 and the internal oil paths formed in the wall of the transmission casing 2b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charge structure for a hydrostatic continuously variable transmission (HST) installed in a work machine such as a tractor.

In general, in a hydrostatic continuously variable transmission, a charge oil path for compensating for hydraulic fluid leakage is connected to a pair of speed change oil paths connecting a hydraulic pump and a hydraulic motor, and the charge pump is driven by engine power. The oil of a predetermined pressure discharged from is supplied to the charge oil passage. As an example thereof, for example, as disclosed in Patent Document 1, a speed change casing incorporating a variable capacity pump and a constant capacity motor, and a port block having a speed change oil path and a charge oil path are provided. The joined hydrostatic continuously variable transmission is connected so that its port block is joined to the front of the transmission case, and the oil discharged from the trochoid charge pump attached to the transmission casing is formed in the transmission casing. It is known that oil is supplied to an oil filter directly attached to the outer surface of the casing via an internal oil passage, and the oil purified here is guided to the charge oil passage of the port block via the internal oil passage formed in the transmission casing. ing.
Japanese Patent Application Laid-Open No. 8-74362

  The above charge structure has the advantage that it can be supplied to the charge oil passage without the need for external piping for oil discharged from the charge pump, but the installation location of the oil filter that requires element replacement is a hydrostatic type. This is limited to the outer periphery of the transmission casing in the continuously variable transmission, and can only be used if the hydrostatic continuously variable transmission is of a specification that is exposed to the outside. Therefore, in a model with a specification in which the hydrostatic continuously variable transmission is surrounded by a housing, etc., the discharge oil from the charge pump is supplied to the filter mounted outside the housing through the piping, and also through the piping. Therefore, it is necessary to supply purified charge oil to the port block. This requires a lot of work for assembling the highly oil-tight piping, and many piping components are necessary, which contributes to high costs.

  When the hydrostatic continuously variable transmission is separated from the transmission case for inspection and maintenance, the oil filter is also removed together with the hydrostatic continuously variable transmission. There was also a risk that the oil filter mounted so as to protrude greatly hit another object to be damaged and deformed.

  The present invention has been made paying attention to such points, and has a high degree of freedom in setting the position of an oil filter for purifying oil discharged from a charge pump, and an oil filter for oil discharged from a charge pump. It is an object of the present invention to provide a charge structure capable of supplying to a charge oil passage purified by an oil filter without using an external pipe.

  According to a first aspect of the present invention, there is provided a hydrostatic continuously variable transmission having a port block connected to a transmission casing, connected to an end face of the transmission case so that the port block is positioned on the transmission case side. Oil installed on the outer surface of the mission case via a port block, gearbox, and an internal oil passage formed in the wall of the mission case. It is configured to guide and supply the oil to the filter, and to guide the oil that has passed through the oil filter to the charge oil passage in the port block through the mission case and the internal oil passage formed in the wall of the transmission casing. Features.

  According to the above configuration, while the oil filter is mounted on the outer surface of the transmission case, the oil supply from the charge pump to the oil filter and the oil supply from the oil filter to the charge oil passage of the port block are the internal oil passage. Will be done through.

  Even if the hydrostatic continuously variable transmission is removed from the transmission case, the oil filter can remain on the transmission case side.

  Therefore, according to the first aspect of the present invention, the charge oil filter can be installed at a suitable position on the outer surface of the transmission case in a state where maintenance such as element replacement can be easily performed, but without using external piping. It is possible to supply purified oil, and it is possible to construct a charge structure excellent in practicality without troublesome piping processing or oil leakage to the outside of the machine at a low cost with few parts. In addition, by leaving the oil filter on the transmission case side during overhaul and maintenance, there is less risk of the oil filter hitting another object and causing damage or deformation.

According to a second invention, in the first invention,
The hydraulic oil derived from the transmission case is supplied to a main oil filter arranged outside the transmission case, and the discharge port of the main oil filter and the suction port of the charge pump are inserted through the transmission case in an oil-tight manner. They are connected by pipes.

  According to the above configuration, the main oil filter and the charging oil filter are used to purify twice while using a lubricating oil containing a large amount of gear wear powder and the like, so that a sufficiently clean charge oil is supplied to the charge oil passage. The function of the hydrostatic continuously variable transmission can be satisfactorily exhibited for a long period of time. Moreover, the oil passage from the main oil filter to the transmission case and the oil passage from the transmission case to the charge pump can be formed with a single suction pipe that penetrates the transmission case in an oil-tight manner. The desired oil path can be formed on the outside and inside of the pipe.

According to a third invention, in the second invention,
The suction pipe is oil-tightly penetrated and fixed to the transmission case, and both ends of the suction pipe are inserted oil-tight into the discharge port of the main oil filter and the suction port of the charge pump, respectively. .

  According to the above configuration, the both ends of the suction pipe need only be inserted into the discharge port of the main oil filter and the suction port of the charge pump. In addition, the number of assembling steps is small, which is effective for cost reduction and productivity improvement.

  FIG. 1 shows a tractor having a charge structure for a hydrostatic continuously variable transmission according to the present invention. This tractor is configured as a monobody type in which an engine 1, a clutch housing 2, and a transmission case 3 are sequentially connected in series to form a body body. FIG. 2 shows a transmission system diagram of the traveling system. ing. The clutch housing 2 is composed of a front housing 2a connected to the engine 1 and a transmission casing 2b connected to the rear end thereof, and the transmission case 3 is a mid case 3a connected to the clutch housing 2. And a rear case 3b connected to the rear end thereof.

  As shown in FIGS. 2 and 3, a dry main clutch 4 is incorporated in the front housing 2 a of the clutch housing 2, and a hydrostatic continuously variable transmission 5 as a main transmission is installed in the transmission casing 2 b of the clutch housing 2. The output of the engine 1 is input to the input shaft (pump shaft) 5 a of the hydrostatic continuously variable transmission 5 through the main clutch 4 and the gear transmission 6. The shift power extracted from the output shaft (motor shaft) 5b of the hydrostatic continuously variable transmission 5 is transmitted to the transmission case 3 and gear-shifted in three stages by the auxiliary transmission 7, and the final shifted power is rear While being transmitted to the left and right rear wheels 9 via the differential device 8, a part of the finally shifted power is taken out and transmitted to the front differential device 12 of the front axle case 11 via the transmission shaft 10. A four-wheel drive type traveling transmission system is configured in which front wheels 13 that are steerable on the left and right sides of the axle case 11 are driven. A part of the power transmitted to the input shaft 5 a is branched and transmitted to the PTO shaft 14 provided at the rear end of the transmission case 3 via a multi-plate type PTO clutch 15.

  A port block 21 is connected to a rear end surface of the transmission casing 2b in the clutch housing 2 so as to be located inside a joint connection portion with the transmission case 3 to form an oil-tight transmission chamber 22. In addition, a variable displacement pump 5P configured as an axial plunger type and a constant variable displacement motor 5M are axially supported in parallel on the left and right. As shown in FIG. 5, the swash plate 16 of the pump 5P is operated to change the angle by a hydraulic servo device 17 that is controlled to operate based on a shift pedal operation.

  As shown in the hydraulic circuit diagram of FIG. 11, the port block 21 is provided with a pair of speed change oil passages a and b for connecting the pump 5P and the motor 5M, and a charge oil passage c. As described above, by changing the flow direction and flow rate of the pressure oil discharged by the swash plate angle changing operation of the pump 5P, the rotation direction and the rotation speed of the motor 5M can be changed to enable forward / reverse switching and zero start. A continuously variable transmission can be performed.

  When the oil pressure on the high pressure side exceeds the set value, a safety valve 23 is connected to each of the oil passages a and b for shifting, and the oil passages a and b for shifting each have a check valve 24. Is connected to the charge oil passage c, and the oil of the pressure set by the charge relief valve 25 is replenished to one of the transmission oil passages a and b on the low pressure side.

  The charge pump CP for supplying oil to the charge oil passage c is constituted by a trochoid pump driven by the input shaft 5a of the speed change pump 5P, and is attached to the rear surface of the port block 21. As shown in FIGS. 6 and 7, the discharge port d of the charge pump CP is connected in communication with the internal oil passage e of the port block and the internal oil passage f formed in the wall of the transmission casing 2b. An oil passage f is connected to an internal oil passage g formed in the wall of the mission case 3 via a connection sleeve 26 interposed in an oil-tight manner at the case joining portion. Further, as shown in FIG. 8, a cartridge type oil filter 28 is screwed into a filter mounting seat 27 formed on the lateral outer surface of the mission case 3, and an inflow formed as an annular groove in the filter mounting seat 27. The oil passage h is connected to the internal oil passage g, and the oil sent from the charge pump CP is used as the internal oil passage e of the port block 21, the internal oil passage f of the transmission casing 2b, and the internal oil passage of the transmission case 3. g and the inflow oil passage h, and flows into the oil filter 28.

  A filter mounting screw hole i formed at the center of the filter mounting seat 27 serves as an oil passage for purifying the purified oil flowing out from the center of the oil filter 28. The internal oil passage j formed in the wall of the case 3 is connected in communication, and the internal oil passage j is connected to the internal oil passage k formed in the wall of the transmission casing 2b, and the case joint portion is oil-tight. The internal oil passage k is connected to the charge oil passage c of the port block 21 through a connection sleeve 29 interposed therebetween.

  Further, as shown in FIG. 9, a cartridge type main oil filter 32 is disposed laterally through a stay 31 on the lateral outer side opposite to the mission case 3. A mounting bracket 32 a for the main oil filter 32 is provided with one inlet m and two outlets p and q, and the inlet m is connected to the lower part of the transmission case 3 via a pipe 33. As shown in the hydraulic circuit diagram of FIG. 11, the lubricating oil stored in the transmission case 3 is purified by the strainer 34 and the main oil filter 32, and most of the purified oil is taken out from one discharge port p, and the engine 1 A part of the purified oil supplied to the main pump MP attached to the main pump MP through the main suction pipe 35 is taken out from the other discharge port q, and one suction is supplied to the suction port r of the charge pump CP. It is supplied by a pipe 36.

  The suction pipe 36 connecting the discharge port q of the main oil filter 32 and the suction port r of the charge pump CP is fitted through the peripheral wall of the mission case 3, and a mounting flange 36 a provided in the middle of the pipe is provided outside the mission case 3. It is connected and fixed to the side face in an oil-tight manner via a packing 37, and both ends of the suction pipe 36 are inserted into the discharge port q of the main oil filter 32 and the suction port r of the charge pump CP, respectively, and sealed with an O-ring 38. It has been stopped.

  [Other Examples]

  (1) In the above embodiment, a part of the clutch housing 2 is used as a speed change casing of the hydrostatic continuously variable transmission 5. However, a hydrostatic type is formed by joining and connecting a dedicated speed change casing and the port block 21. The continuously variable transmission 5 is configured, and the independent hydrostatic continuously variable transmission 5 is connected to the end of the transmission case 3 so that the hydrostatic continuously variable transmission 5 is accommodated in the clutch housing 2. It can also be implemented.

  (2) In the above embodiment, the oil purified by the main oil filter 32 is supplied to the main pump MP and the charge pump CP. However, a primary oil filter dedicated to the charge pump can be provided.

Overall side view of tractor Aircraft body side view Schematic diagram of transmission system Vertical side view showing a part of the transmission system Transverse plan view showing a part of the transmission system Cross-sectional plan view showing the suction system of the charge pump Cross-sectional plan view showing part of the discharge system from the charge pump Cross-sectional plan view showing part of the discharge system from the charge pump Partially cutaway front view showing the charge pump suction system Longitudinal front view of oil filter connection Hydraulic circuit diagram

Explanation of symbols

2b Transmission casing 3 Transmission case 5 Hydrostatic continuously variable transmission 21 Port block 28 Oil filter 32 Main oil filter 36 Suction pipe c Charge oil passage e Internal oil passage f Internal oil passage g Internal oil passage j Internal oil passage k Internal oil Road q Discharge port r Inlet port

Claims (3)

  A hydrostatic continuously variable transmission comprising a port block connected to a speed change casing is connected to the end face of the transmission case so that the port block is located on the mission case side, and a charge is applied to a position on the transmission case side of the port block. Equipped with a pump, the oil discharged from the charge pump is guided and supplied to the oil filter mounted on the outer surface of the transmission case through the port block, the transmission casing, and the internal oil passage formed in the wall of the transmission case. The hydrostatic type is characterized in that the oil that has passed through the oil filter is guided to the charge oil passage in the port block through an internal oil passage formed in the wall of the transmission casing and the transmission casing. Charge structure of continuously variable transmission.   The hydraulic oil derived from the transmission case is supplied to a main oil filter disposed outside the transmission case, and the discharge port of the main oil filter and the suction port of the charge pump are inserted through the transmission case in an oil-tight manner. 2. A charging structure for a hydrostatic continuously variable transmission according to claim 1, wherein the charging structure is connected by a pipe. 3. The suction pipe is fixed to the transmission case in an oil-tight manner, and both ends of the suction pipe are inserted in an oil-tight manner into the discharge port of the main oil filter and the suction port of the charge pump, respectively. The charge structure of the described hydrostatic continuously variable transmission.

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